The invention relates to a practical system for locating a selected vehicle from which an alarm signal is generated. More particularly, this invention concerns a system for automatically locating an automobile which is broken into and automatically tracking its position if it is driven away and for expeditiously dispatching police cars to it or intercepting it respectively.
The statistics on passenger vehicle or car theft in the United States are mind boggling and exceed one million cars a year. Insurance rates are climbing at an alarming rate and there are few if any feasible solutions in sight. The current car protection equipment available to individual car owners include a range of features and capabilities.
Specifically, the current available equipment can be categorized as localized alarm system protection, car location systems and fleet management systems. The localized alarm protection systems activate a warning device such as a siren when the car is broken into. Generally speaking this type of system is effective only if the car owner or the police are in the vicinity. Other people tend not to get involved in this situation and in many cases car alarm sounds are not being acted on by the police. The pros are that they are inexpensive and in some cases the warning device deters theft. The cons are that if the owner is not around there is a high likelihood that no action will be taken to apprehend the intruder. Also if the owner is around and is able to get to the vehicle he may be risking personal injury or worse, by the intruder. Car location systems will identify the location of the car after the fact, that is sometime after the intrusion is detected and the car is driven away from its parking spot. A good example of such a system is disclosed by U.S. Pat. No. 4,177,466 to Reagan. While there is a relatively high likelihood that the car will be eventually located, this type of system suffers from some distinct practical shortcomings, some of which are technical and some of which are political. The pros are that there is a relatively high livelihood that the stolen car will be located and returned to the rightful owner. The cons are that the car owner must notify the police that his car is missing before the police can take any search action. The problem is that if the owner is not around it may take sometime before he becomes aware that the car is missing and by then the car may be extensively vandalized. Furthermore such a system does not prevent nor deter stealing. Also because the system such as disclosed by the Reagan patent is based on esoteric infrastructure requiring very specialized antenna sites and equipment, it is quite expensive. Furthermore the state police are very reluctant to finance such a system. As such the system is available only in Massachusetts and even there the inventor had to donate the required equipment to the police before they were willing to use it. Furthermore, the car location system as disclosed in the Reagan patent utilizes location stations having location indicators, the latter comprising proximity detectors and/or radio direction finders. These location stations may be placed at fixed locations or carried by driver-operated finder vehicles. Another car location system of a different type, such as disclosed in U.S. Pat. No. 3,922,678 to Frenkel, utilizes a plurality of wireless signal detecting and relaying means which must be equidistantly spaced from one another in a fixed array, all of which respond to an alarm signal from a wireless signal generating means carried by a mobile source located within a zone in their detection region, and each of which respond and transmit at frequencies differing from one another. A plurality of receivers are also required at a central control station such as police headquarters. Each of these receivers are tuned to receive signals of different frequencies corresponding in frequency to the signals transmitted by the relaying means to thereby determine the zone within which said mobile source is located and track its movement. Each zone corresponds to a particular area of a map within which the relays are arrayed and each zone is identified by one of a plurality of lamps disposed on the map, each lamp of which is responsive to those wireless detecting means which detect a mobile source located within a zone in their detection region. This type of system is also impractical in that it requires the construction of a fixed array of specialized antenna sites each of which are equidistantly spaced from one another, an expensive proposition and impractical in most densely populated urban areas. Fleet management systems are geared toward specialized application in truck fleet management. It is somewhat outside the scope of this discussion in that it is geared toward very large truck fleet owners who keep tabs on their vehicles. An example of the type of system utilize for fleet management are those which include LORAN -C transmitters. The elements of automatic car location and "alarm" detection are available on these systems, but the link to a monitoring central alarm station is beyond the realm of financial feasibility to an individual who would use such a system to protect against theft of his own car. The bulkiness and expense of such equipment effectively rules it out as a viable alternative in the individual car alarm and location detection market.